The new High-Definition Multimedia Interface (HDMI) standards (versions 1.4 and 1.4a), defining an interface for transmission of decoded programs to final player equipment, provide for transfer of full-resolution high-definition 3D video streams, i.e. transfer of two stereoscopic full-resolution HD views, which doubles the transmission pass band. This pass band is not available on current transport infrastructures (satellite, DTTV, cable).
Pending a transport infrastructure dedicated to 3D programs, the interested parties and normalization committees (DVB, HDMI, MPEG) are working on approaches enabling 3D video to be transmitted on existing transport infrastructures. The progress is published on the Websites of these committees. It is sought to insert two views in place of each image in the transported stream and, by way of minor modifications to the reception equipment, to reconstruct the two views in a format compatible with the HDMI standard. As existing transport infrastructures are not designed for this, the resolution of the views may have to be downgraded.
Among the different transport formats that have been reviewed, two generic candidates have been identified: Top-and-Bottom (TaB) and Side-by-Side (SbS). Each of these generic formats can be combined with an existing 2D high definition (HD) format of the progressive type, i.e. the 50 Hz and 60 Hz variants of the 720p format and the 1080p format at 24 Hz. Only the SbS generic format is combined with the 50 and 60 Hz variants of the 1080i interlaced format.
FIG. 1a represents an HD image according to the TaB format, i.e. a composite image. The top half of the image comprises the left stereoscopic view L at half the vertical resolution, and the bottom half comprises the right stereoscopic view R, also at half the vertical resolution.
FIG. 1b represents an HD image, also composite, according to the SbS format. The left half of the composite image comprises the left stereoscopic view L at half the horizontal resolution, and the right half of the composite image comprises the right stereoscopic view R, also at half the horizontal resolution.
FIGS. 2a to 2c illustrate decimation matrices that have been proposed for reducing the resolution of the stereoscopic images so as to be able to transport the latter in TaB or SbS format.
The complementary matrices of FIG. 2a enable one line out of two to be kept to create an image in TaB format (FIG. 1a). The top matrix keeps the odd lines and the bottom matrix keeps the even lines.
The complementary matrices of FIG. 2b enable one column out of two to be kept to create an image in SbS format (FIG. 1b). The top matrix keeps the odd columns and the bottom matrix keeps the even columns.
The matrices of FIG. 2c, called quincunx (checkerboard) matrices, enable one pixel out of two to be kept per line and per column. In the top matrix, the process starts from a pixel in the top left corner. The bottom matrix defines the complementary decimation. The pixels kept by application of these matrices are compacted by lines for the TaB format or compacted by columns for the SbS format.
There appears to be no consensus on the choice of decimation matrices. The CableLabs consortium is the first to propose a choice in the document OpenCable Specifications, Content Encoding Profiles 3.0 Specification, C-SP-CEP3.0-I01-100827, section 10.2, sub-paragraph #6, published on their Website on Aug. 27, 2010. It proposes using the same matrix for all the images, more precisely one of the matrices of FIG. 2a. 
FIG. 3 schematically illustrates an example of a reception chain of TaB composite images. The composite images 10 reach a vertical interpolator 12 at the refresh frequency, for example, 60 Hz. The interpolator completes the left half-resolution image L of the composite image with the missing lines and then does the same with the right half-resolution image R. The interpolator works at twice the refresh frequency (120 Hz) and supplies the two obtained, left and right, full-resolution HD images to an HDMI transmission circuit 14 at this frequency. Circuit 14 assembles the left and right images into a double-resolution image 16, for example, of double height, and transmits the latter at the initial refresh frequency (60 Hz) to a 3D display. To process SbS composite images, interpolator 12 would be replaced by a horizontal interpolator completing the half-resolution images with the missing columns. It is noteworthy that these transmission techniques divide the spatial resolution of the stereoscopic views by 2.